Facile synthesis of N‐(methyl and phenyl)‐Δ4‐isoxazolines via the reaction of (Z)‐N‐(methyl and phenyl)‐C‐arylnitrones with dimethyl acethylenedicarboxylate, DMAD, in ionic liquid is described. (Z)‐N‐methyl‐C‐arylnitrones afforded the high yield of N‐methyl‐Δ4‐isoxazolines 4a, 4b, 4c, 4d, 4e in ionic liquid, [bmim]BF4, at room temperature. However, the reaction of (Z)‐N‐phenyl‐C‐arylnitrones with DMAD afforded the mixtures of cis and trans isomers of related N‐phenyl‐Δ4‐isoxazolines (5a, 5b, 5c, 5d, 5e, 5f, 5g, 5h, 5i, 5j, 6a, 6b, 6c, 6d, 6e, 6f, 6g, 6h, 6i, 6j) under these conditions. J. Heterocyclic Chem., (2012).